Unlike non-rechargeable batteries, rechargeable batteries may be recharged. Non-aqueous electrolyte rechargeable batteries with high energy density have recently been developed as high power rechargeable batteries. Lower power batteries in which battery cells are made into a battery pack are used as the power source for various portable electronic devices such as cellular phones, laptop computers, and camcorders. Larger battery packs which are formed by connecting several to tens of the rechargeable battery cells may be suitable for motor driven devices such as the electric vehicles.
Rechargeable batteries may be classified into different categories based on external shape, for example, rectangular box and cylindrical shapes. Rechargeable batteries include an electrode assembly in which a long rectangular-shaped positive plate, a long rectangular-shaped negative plate, and a separator that is interposed between the plates are spiral-wound together. Alternatively, a positive plate, a negative plate, and a separator may be stacked in a multiple layer structure. The electrode assembly is inserted into a container, and a cap assembly is mounted on the container to form the battery.
The cap assembly of such rechargeable batteries has an external terminal that is coupled to the electrode assembly. The cap assembly is fixed to the container by welding, etc. to seal the container.
Generally, the external terminal of the cap assembly is inserted into a hole that is formed on the cap plate of the cap assembly. Then, a packing and an O-ring are disposed between the hole and the external terminal to provide electrical insulation and a tight fit.
The external terminal is coupled with the cap plate by a nut that is fastened to a screw thread formed on the outer circumferential surface of the external terminal. The packing and O-ring are pressed against the nut to seal the hole.
However, the above sealing structure and installation of the external terminal is problematic because it requires many parts which raise the manufacturing cost, and complicates the manufacturing process which decreases the manufacturing efficiency.